A short and novel synthesis of carbocyclic nucleosides and 4′-epi-carbocyclic nucleosides from 2-cyclopenten-1-ones

Synthesis of 2'-fluoro and 2',4'-dimethyl pyrimidine C-nucleoside analogues as potential anti-HCV agents

Stereoselective synthesis of novel 2'-fluoro and 2',4'-dimethyl carbocyclic pyrimidine C-nucleoside analogues using selective fluorination of an epoxide opening reaction is described. The key fluorinated intermediate 7 was prepared from the epoxide intermediate 5 via selective ring opening of the epoxide. Synthesis of isonucleosidic bases through the mesylate 7 and final deprotection provided the target carbocyclic pyrimidine C-nucleoside analogues. The synthesized compounds 15 and 18 were evaluated as inhibitors of the hepatitis C virus (HCV) in the Huh-7 cell line in vitro.

Synthesis and anti-HCV evaluation of 4'(alpha)-ethyl and 2'(beta)-methyl-carbodine analogues

Novel 4'(alpha)-ethyl-2'(beta)-methyl carbocyclic nucleoside analogues have been prepared and evaluated for inhibition of hepatitis C virus (HCV) RNA replication in cell culture. The construction of cyclopentene intermediate 12 beta was successfully made via sequential Johnson-Claisen orthoester rearrangement and ring-closing metathesis (RCM) starting from Weinreb amide 5. Selective dihydroxylation and desilylation gave the target carbodine analogues. The synthesized nucleoside analogues mentioned above 18 and 19 were assayed for their ability to inhibit HCV RNA replication in a subgenomic replicon Huh7 cell line (LucNeo#2). However, the synthesized nucleosides neither showed any significant antiviral activity nor toxicity up to 50 microM.

Molecular recognition in the P2Y(14) receptor: Probing the structurally permissive terminal sugar moiety of uridine-5'-diphosphoglucose

The P2Y(14) receptor, a nucleotide signaling protein, is activated by uridine-5'-diphosphoglucose 1 and other uracil nucleotides. We have determined that the glucose moiety of 1 is the most structurally permissive region for designing analogues of this P2Y(14) agonist. For example, the carboxylate group of uridine-5'-diphosphoglucuronic acid proved to be suitable for flexible substitution by chain extension through an amide linkage. Functionalized congeners containing terminal 2-acylaminoethylamides prepared by this strategy retained P2Y(14) activity, and molecular modeling predicted close proximity of this chain to the second extracellular loop of the receptor. In addition, replacement of glucose with other sugars did not diminish P2Y(14) potency. For example, the [5'']ribose derivative had an EC(50) of 0.24muM. Selective monofluorination of the glucose moiety indicated a role for the 2''- and 6''-hydroxyl groups of 1 in receptor recognition. The beta-glucoside was twofold less potent than the native alpha-isomer, but methylene replacement of the 1''-oxygen abolished activity. Replacement of the ribose ring system with cyclopentyl or rigid bicyclo[3.1.0]hexane groups abolished activity. Uridine-5'-diphosphoglucose also activates the P2Y(2) receptor, but the 2-thio analogue and several of the potent modified-glucose analogues were P2Y(14)-selective.

Carbocyclic 3'-deoxyadenosine-based highly potent bisubstrate-analog inhibitor of basophilic protein kinases

Carbocyclic analogs of 3'-deoxyadenosine were synthesized as racemates and the resulting stereoisomers were separated by chromatography on a chiral column. The conjugation of obtained compounds with hexa-(D-arginine) via 6-aminohexanoic acid linker led to a highly potent inhibitor of several basophilic protein kinases with some selectivity towards cAMP-dependent protein kinase.

Microwave-assisted N-nitroarylation of some pyrimidine and purine nucleobases

An efficient procedure for the synthesis of some N-nitroaryl derivatives of nucleobases via microwave-assisted N-nitroarylation of nucleobases in the presence of SiO2 and Cs2CO3 in DMSO, as the homogenizing solvent, is described. In this method, some pyrimidine and purine nucleobases are nitroarylated regioselectively in moderate to high yields and short reaction times.Key words: microwave, N-nitroarylation, pyrimidine, purine, SNAr.